Gas turbine engines, such as those used for aircraft propulsion, typically include a bleed valve arrangement for diverting pressurized working medium fluid from a main flow path. One common use of such a valve arrangement is to channel fluid, as necessary, from the engine's primary flow path to a coannular secondary flow path to temporarily improve the aerodynamic stability of the engine's compression system.
It is common to bleed a portion of the inlet air from a gas turbine engine for a variety of purposes. Common purposes include providing a pressure differential on opposite sides of bearing seals to preclude oil leaks, to cool or heat components of the turbojet engine to control operational clearances, or to provide air conditioning or warm air to an aircraft cabin.
Typically, the air is tapped or bled at the gas turbine engine compressor and can be tapped between the low pressure compressor and the high pressure compressor, or from the cold air flow when the turbojet engine is of the turbo fan type. The selection of the source of the bleed air depends upon the desired temperatures and pressures of the air.
A drawback with some diffusers is that the diffusers project into the gas turbine engine fan stream even when not in operation so as to impede airflow and decrease engine performance.
In view of the foregoing, it is an object of the present invention to provide a bleed diffuser for a gas turbine engine that overcomes the above-mentioned drawbacks and disadvantages.